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The Dawn spacecraft, after more than seven years in space, has entered the final phase of its trek to Ceres.

NASA said Wednesday that Dawn is now about 640,000 kilometers from the dwarf planet and is expected to arrive in orbit on March 6.

Ceres is the largest object in the asteroid belt, with an average diameter of about 950 kilometers.

Dawn’s visit to Ceres will make it the first spacecraft ever to orbit two different celestial objects. The probe also orbited the protoplanet Vesta in 2011-2012.

Although discovered more than 200 years ago, scientists know little about Ceres. The closest dwarf planet to Earth, it may have both an ocean and an atmosphere. Ceres is so cold that water would sublimate if it wre on the surface.

The Kepler Space Telescope, restored to functionality after suffering damage to stabilizing wheels, has discovered an exoplanet.

The planet is 2.5 times the size of Earth and is about 180 light years away. It has a mass about 12 times that of Earth.

Andrew Vanderburg, a graduate student researcher at Harvard-Smithsonian Center for Astrophysics, and his colleagues noticed data that indicated the existence of the exoplanet when they examined the results of a February test to determine whether the Kepler Space Telescope could be restored to service.

The researchers confirmed the detection of HIP 116454b by using a spectrograph on the Telescopio Nazionale Galileo.

Transits of HIP 116454b were also confirmed by the Microvariability and Oscillations of STars (MOST) satellite.

“Like a phoenix rising from the ashes, Kepler has been reborn and is continuing to make discoveries,” Vanderburg said. “Even better, the planet it found is ripe for follow-up studies.”

The Kepler Space Telescope uses a camera to detect the dimming of a star when a planet passes in front of it.

After two of the telescope’s four reaction wheels failed, the telescope was unable to maintain a focus on distant stars. Engineers devised a method of using pressure from photons emitted by the sun to balance the spacecraft.

NASA said in May that the renewed Kepler mission, dubbed K2, would continue for two years.

The Kepler Space Telescope has discovered 996 confirmed exoplanets, according to the mission website maintained by NASA.

Paleontologists have identified a species of horned dinosaur that lived in Montana more than 100 million years ago, the oldest known ceratopsian in North America.

The two foot-long animal – about as long as a crow or a raven – was an ancestor much larger horned and frilled creatures that roamed Cretaceous period landscapes on the continent.

Known as Aquilops americanus, the animal is a clue to a pattern of dinosaur migration from Asia to North America.

“Aquilops lived nearly 20 million years before the next oldest horned dinosaur named from North America,” Andrew A. Farke, a paleontologist at the Raymond A. Alf Museum of Paleontology in Claremont, Calif. and lead author of a paper documenting the discovery. “Even so, we were surprised that it was more closely related to Asian animals than those from North America.”

Those relatives included Liaoceratops yanzigouensis, another tiny predecessor of Triceratops, Styracosaurus, and other ceratopsian dinosaurs whose fossils were discovered in China and described in 2002.

Researchers found only the remnants of one, probably adolescent, Aquilops’ skull, about 84 millimeters long. But those bones are distinctive enough to set the fossils apart as a holotype. Among the most distinctive features of the skull is a downward-curving, bumped beak.

The Aquilops americanus fossils were found in 1997. The name means “American eagle face.”

The paper documenting the discovery was published in the Dec. 10 edition of PLOS One.